Known in the past has been an automatic transmission provided with a torque converter and a transmission mechanism. The torque converter and transmission mechanism are supplied with hydraulic oil for operation and lubrication. However, if the hydraulic oil is low in temperature, the hydraulic oil rises in viscosity and the drive resistance in the automatic transmission increases.
For this reason, when the hydraulic oil is low in temperature such as when starting up a vehicle, it is desirable to be able to raise the temperature of the hydraulic oil. In the hydraulic oil temperature control device described in PTL 1, to reduce the effect on the acceleration performance of the vehicle, the hydraulic oil is increased in temperature when the vehicle is decelerating. Further, in the control device of an automatic transmission described in PTL 2, when using the transmission mechanism to change the gear, an engagement element of the transmission mechanism slips, and therefore the hydraulic oil is increased in temperature.